This invention relates to hinge joints and is more particularly concerned with improvements in hinge joints which are particularly adapted for connecting link elements of a track for an endless track vehicle.
Hinge joint arrangements for connecting track links have heretofore been employed which have included various type seals and in which a track link counterbore has served as a seal cavity. In such arrangements, all mating parts must be held to very close tolerances which gives rise to increased costs in manufacturing and to assembly problems when the tolerance requirements are not met. This type of hinged joint when pressed together to form a track rail assembly becomes a blind assembly which is controlled by location of the holes in the track link for mounting the track shoes. In most cases, due to the number of mating parts, and the relationship to each other, the sealing of such joints is very difficult.
In the commonly used track assembly hinge joint there is a radial space between the track bushing and track pin which allows for uneven loading between the pin and bushing and results in a much greater wear rate than normal. Also, this radial spacing between the track bushing and the track pin permits a considerable amount of abrasive contaminants to enter when the seal fails and produces rapid deterioration of the hinged joints so that frequent repair or replacement of the deteriorated elements of the track mechanism is required. Other difficulties arising from the loose fit between the bushing include track stretching, which is referred to as pitch elongation. When the track stretches and the distance from one bushing to the next increases, the track pitch no longer matches sprocket pitch and the bushing starts to ride up in the tooth resulting in wear on the tooth and on the outside of the bushing, with the track becoming snaky and the sprocket teeth gouging into the links. Loose snaky track caused by bushing and pin wear speeds up wear of the roller flanges and link rails due to the slamming action of the links against such members.
It is a general object of the present invention to provide an improved joint arrangement of this type which reduces wear, which minimizes damage when there is any seal failure, and which can be manufactured and assembled with greater economy than the joint arrangements of similar character heretofore employed.
It is a more specific object of the present invention to provide a new and improved hinge joint arrangement which is particularly adapted for connecting track links of endless track vehicles.
It is a further object of the invention to provide a track link hinge joint connection which is more wear resistant than the joints presently employed and which minimizes track stretching so as to avoid development of a snaky track condition and the difficulties resulting from such a track condition.
Another object of the invention is to provide a track hinge joint structure in which the washer used for thrust control is allowed to float between the pin and the seal with the washer held in contact with the end face of the bushing and thereby eliminating the risk of developing metal fragments which otherwise frequently result from contact between the bushing and the metal spacer and which may migrate into the bushing especially when the track is working on a side slope.
Still another object of the invention is to provide a hinge joint of the type described in which self-lubricating bearing elements are employed between the bushing and the pin and also between the end of the bushing and the thrust control ring so that the bushing fits on the pin with a minimum degree of looseness thereby reducing wear and track stretching and in which an efficient sealing arrangement is employed for preventing entry of contaminants and absorbing end thrust with the seal adapted to be installed in pre-assembled relation in the bushing end of the link and eliminating any need for a counterbore and the close tolerances heretofore required in this type installation.
The invention which is claimed herein comprises a hinge joint construction of the type in which one hinge element in the form of a bushing is mounted on a hinge pin which comprises the cooperating hinge element, with provision for some degree of axial movement of the bushing on the pin, together with bearing and sealing elements which comprise a self-lubricating bearing sleeve disposed between the pin and the bushing and a self-lubricating bearing washer between the end face of the bushing and an end thrust control ring on the pin on which an element of an end seal assembly is carried with a cooperating seal element seated in a bore in which the end of the bushing is mounted.
The foregoing objects and other objects and advantages of the invention will become more apparent when reference is made to the accompanying detailed description of the preferred embodiment of the invention which is set forth therein and shown in the accompanying drawings wherein like reference numerals indicate corresponding parts throughout.